2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

S5 tll powerless acceleration

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Old Sep 30, 2011 | 10:25 AM
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From: Healy AK
S5 tll powerless acceleration

So I just picked up a tll vert 1990 with a s5 tll engine. Anyways it has a very rough idle until it warms up, and once warmed up it will still periodically just drop idle then die. It also has like a 1 second response hesitation from idle if you step on the gas before it starts to increase rpms, but is fine above 1600 rpms. And it really has no power at all until about 2800-3000rpms. Any ideas or suggestions would be great I'm doing a major tune up on it this weekend
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Old Sep 30, 2011 | 10:54 AM
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Start by adjusting your throttle position sensor. While you're doing the tune up, check for vacuum leaks with a can of carb cleaner while the engine idles.
The delay is probably due to the secondary throttle plates being removed or stuck. Strangely the behavior will be about the same. Has the throttle body been modified?
What is your reference when you say "no power"? Are you comparing it to an NA rx7, stock turbo rx7 or an LS1? Turbo rotaries are not known for low rpm torque.
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Old Sep 30, 2011 | 11:11 AM
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From: Healy AK
This is my first turbo fc I've just had all NA fcs so I understand it's gonna have a lot less torque, put this is like almost a sputter acceleration untill like 1600rpms and will not go unless I give it a little excessive gas to get going
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Old Sep 30, 2011 | 11:13 AM
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From: Healy AK
Also other problem is the gas pedal gas to be pumped like a mad man to get it to start and once it's warmed up if it dies it's very hard to start until it cools or sits for like 5 min
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Old Sep 30, 2011 | 11:58 AM
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sounds like a vacuuum leak.
check all hoses to the intake,and the intake,injector area for leaks.
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Old Sep 30, 2011 | 12:12 PM
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From: Healy AK
Well I do know most of the vacuum lines are removed and it has a lot of block off plates on it, but I gonna tear it into and check everything, new plugs new wires and just recheck all the IC couplers and few vacuum lines and clean her up
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Old Sep 30, 2011 | 12:47 PM
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If the previous owner stripped all the emissions stuff, the throttle body is probably modified. More info here ->http://fc3spro.com/TECH/HOWTO/TBM/tbm.html Note the bogging under 3000 rpm.
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Old Sep 30, 2011 | 01:44 PM
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From: Healy AK
Tyvm
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Old Sep 30, 2011 | 02:09 PM
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From: Healy AK
Just outta curiosity would those mods to the intake make me have to pump the gas pedal to get it started?
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Old Sep 30, 2011 | 02:36 PM
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Originally Posted by The Wildchild
Just outta curiosity would those mods to the intake make me have to pump the gas pedal to get it started?
The mods could cause a vacuum leak if not done correctly. They also make the car difficult to start/idle cold if the cold start thermowax and BAC were removed.
Pumping the gas pedal in an EFI car doesn't work like it does in a carb'd car. In an s5, flooring the gas pedal during cranking will cut fuel. It was a response to hot start issues. Try flooring it when the car is cranking then release the pedal when the car starts firing.
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Old Sep 30, 2011 | 04:39 PM
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From: Healy AK
Alright thanks for all the great info I'll look into everything this afternoon and let you know what I have figured out
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